In a generic method, a sequence of strip patterns of the same strip direction which are formed in each case from a multitude of strips is projected by way of a projecting device onto a surface to be measured, wherein in each case at least one picture of the surface is taken by a camera or by each of at least two cameras, during the projection of each of the strip patterns. Corresponding points in picture planes of the camera and of the projection device or in picture planes of the cameras are then identified by way of the strip pattern projected onto the surface, whereupon spatial coordinates of surface points on the surface are determined by triangulation on the basis of the points identified as corresponding.
Such methods e.g. are known from the documents DE 10 2007 022 361 A1 and DE 10 2006 049 695 A1. Sometimes, such methods envisage some of the projected strip patterns being phase-shifted strip patterns with a sinusoidal brightness course, which permit a phase value to be assigned to each point on the surface, whilst some further ones of the projected strip patterns define a grey code, which permits the resolution of ambiguity which still remains after determining the phase values.
A difficulty which results with such triangulation methods which are based on pattern projection lies in a comparatively large number of patterns having to be projected and accordingly many pictures having to be taken, so that the corresponding or homologous points in the picture planes can be identified unambiguously and sufficiently accurately, which of course cannot be effected in an infinitely short time. For this reason, the measurement of surface contours with the methods of this type which are known from the state of the art demands a comparatively long measurement duration. This is disadvantageous for many applications, in particular if moved surfaces are to be measured or if a hand-held apparatus is to be used for this.